UIImageView & Error 101

RobTucker11 · January 2009

I'm trying to build a simple animation. When running in the simulator it works fine. When trying to run on the device, it crashes. From the research i've done it appears as though the issue is with how i'm loading my images into the array for the image view.
Here is the code from my ViewController.m File. There are some other parts, but it crashes before it gets to them.


@synthesize mainImage, buttonClicked, radarImagesArray, analyzingImagesArray, arr1;
- (void)viewDidLoad {
	int counter = 1;
	mainStatus = 0;
	[buttonClicked setImage: [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@\"analyze\" ofType:@\"png\"]] forState:UIControlStateNormal];
	arr1 = [[NSMutableArray alloc] init];
	[arr1 addObject:@\"image1\"];
	[arr1 addObject:@\"image2\"];
	
	NSString *temp;
	UIImage *tempImage;
	temp = [[NSString alloc] init];
	tempImage = [[UIImage alloc] init];
	radarImagesArray = [[NSMutableArray alloc] init];
	analyzingImagesArray = [[NSMutableArray alloc] init];
	for(int x = 1; x <= 75; x++){
		
		NSString *holder = [[NSString alloc] init];
		if(counter < 10){
			holder = [NSString stringWithFormat: @\"00\"];	
		}
		
		if(counter >= 10 && counter < 100){
				holder = [NSString stringWithFormat: @\"0\"];
		}
		
		temp = [NSString stringWithFormat:@\"iStock_000003493496Small We %@%i\", holder, x];	
		tempImage = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:temp ofType:@\"jpg\"]];
		if(tempImage){
			[radarImagesArray addObject: tempImage];
			//[tempImage release];
			//[tempImage dealloc];
		}
		//if(temp)[temp release];
		
		counter++;
		
	}
	counter = 1;
	for(int x = 1; x <= 20; x++){
		
		NSString *holder = [[NSString alloc] init];
		if(counter < 10){
			holder = [NSString stringWithFormat: @\"00\"];	
		}
		
		if(counter >= 10 && counter < 100){
			holder = [NSString stringWithFormat: @\"0\"];
			
		}
		
		temp = [NSString stringWithFormat:@\"iStock_000004494873Small We %@%i\", holder, x];
		tempImage = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:temp ofType:@\"jpg\"]];
		if(tempImage){
			[analyzingImagesArray addObject: tempImage];
			//[tempImage release];
		}
		//if(temp)[temp release];
		counter++;
	}
	
	[mainImage setAnimationImages: radarImagesArray];
	[mainImage startAnimating];
    [super viewDidLoad];
}

Here is the code from my .h



#import <UIKit/UIKit.h>

@interface MandarViewController : UIViewController {
	IBOutlet UIImageView *mainImage;
	IBOutlet UIButton *buttonClicked;
	NSMutableArray *radarImagesArray;
	NSMutableArray *analyzingImagesArray;
	NSMutableArray *arr1;
	int mainStatus;
}
@property(nonatomic, retain) UIImageView *mainImage;
@property(nonatomic, retain) NSMutableArray *radarImagesArray;
@property(nonatomic, retain) NSMutableArray *analyzingImagesArray;
@property(nonatomic, retain) NSMutableArray *arr1;
@property(nonatomic, retain) UIButton *buttonClicked;
-(IBAction)buttonClicked:(id)sender;
-(void)stopBuildingAnalyzingImagesArray;
@end

I'm somewhat new to the iPhone SDK and cocoa in general and I'm assuming that the issue is something simple that I'm missing. Please HELP!!

RickMaddy · January 2009

How big are your images? Loading them into memory will take 4 bytes per pixel per image.

On a side note, your code (comments added to show issues):


// This is a memory leak because you never release it
NSString *holder = [[NSString alloc] init];
// Using a format of %02d will format an integer as two digit using leading zeros as needed
if(counter < 10){
	// You're not using a format string. Why use stringWithFormat?
	// Just assign a string literal directly: holder = @\"00\";
	holder = [NSString stringWithFormat: @\"00\"];	
}

if(counter >= 10 && counter < 100){
	holder = [NSString stringWithFormat: @\"0\"];
}
		
temp = [NSString stringWithFormat:@\"iStock_000003493496Small We %@%i\", holder, x];

can be changed to:


NSString *temp = [NSString stringWithFormat:@\"iStock_000003493496Small We %02d\", x];

RickMaddy · January 2009

A few more things. Don't start the animation in 'viewDidLoad'. Start it in 'viewDidAppear'.

Also make the call to '[super viewDidLoad]' the first line of code, not the last. This general rule should always be followed when overloading a parent method unless you have a specific reason to call it later in the overloaded method.

RobTucker11 · January 2009

The images are between 12 and 16k each.

Thanks for the tips! I'm new to this. I will move the function over to where you said. As far as the memory leak you mentioned, I didn't see how you said to fix it. Did I miss something? Thanks for the tips!

RickMaddy · January 2009

The images on disk may be 12-14k each but what size in pixels are they? If they are 100x100 that 10,000 pixels which would be roughly 40,000 bytes in memory. If they are 480x320 that's about 614k per image in memory. At 75 images that's 46MB - way too much on a real device.

As for the memory leak, it's no longer there with the suggested code I posted. You have no reason to allocate an NSString object in this case.

bharath2020 · January 2009

Hello RickMaddy,

I am facing problem with loading more number of images into memory. When I load the images from application bundle using imageNamed API of UIImage and add it to UIImageView, The instruments does not show any spike in memory utilization, whereas when I load the image with imageWithContentsOfFile and add it to UIImageView, there's a whole lot of memory utilization.

Is there any difference with imageNamed and imageWithContentsOfFile,

Can I use imageNamed: to load image located at other that application bundle?

Or

How can I add the image into system cache?

RickMaddy · January 2009

imageNamed caches an image. You don't want to use this method to load an image unless it's a small image and you are going to use it a lot. I believe this method only reads files from your resources directory.

If you need to load an image once or you need to use larger images you are better off using imageWithContentsOfFile. Just make sure you release everything when you are done to give the memory back.

bharath2020 · January 2009

Thanks for the reply RickMaddy,

Here are some of my observations which i thought of sharing it.

*Loading an image using imageWithContentsOfFile will not actually load the image into memory. The image is loaded only when it is used for drawing on a view

*Once the image is drawn onto image, we have to explicitly release the image to remove it completely from the memory

* However. Loading an image using imageNamed does not acutally load into memory even it is drawn onto the view( checked the objectAllocation in the instuments and there is trace of this image data). might be it is using the system cache

* imageNamed only loads images from your resources directory

RobTucker11 · January 2009

So it seems as though for doing simple animations with a UIImaveView you are better off using imagedNamed. Am I correct in believing this?

bharath2020 · January 2009

Yes, provided that your images are in resources directory i.e. in your application bundle.

johnqh · January 2009

Forget whether to use imageName. First calculate the RAM needed for the images, as Rick said.

I would have a list of the image file path, but only load the image with imageWithContentOfFile when I need it.

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